/*
- cdissect - determine subexpression matches (with complications)
* The retry memory stores the offset of the trial midpoint from begin, plus 1
* so that 0 uniquely means "clean slate".
^ static int cdissect(struct vars *, struct subre *, chr *, chr *);
*/
static int /* regexec return code */
cdissect(
struct vars *v,
struct subre *t,
chr *begin, /* beginning of relevant substring */
chr *end) /* end of same */
{
int er;
assert(t != NULL);
MDEBUG(("cdissect %ld-%ld %c\n", LOFF(begin), LOFF(end), t->op));
switch (t->op) {
case '=': /* terminal node */
assert(t->left == NULL && t->right == NULL);
return REG_OKAY; /* no action, parent did the work */
break;
case '|': /* alternation */
assert(t->left != NULL);
return caltdissect(v, t, begin, end);
break;
case 'b': /* back ref -- shouldn't be calling us! */
assert(t->left == NULL && t->right == NULL);
return cbrdissect(v, t, begin, end);
break;
case '.': /* concatenation */
assert(t->left != NULL && t->right != NULL);
return ccondissect(v, t, begin, end);
break;
case '(': /* capturing */
assert(t->left != NULL && t->right == NULL);
assert(t->subno > 0);
er = cdissect(v, t->left, begin, end);
if (er == REG_OKAY) {
subset(v, t, begin, end);
}
return er;
break;
default:
return REG_ASSERT;
break;
}
}
/*
- cdissect - check backrefs and determine subexpression matches
* cdissect recursively processes a subre tree to check matching of backrefs
* and/or identify submatch boundaries for capture nodes. The proposed match
* runs from "begin" to "end" (not including "end"), and we are basically
* "dissecting" it to see where the submatches are.
* Before calling any level of cdissect, the caller must have run the node's
* DFA and found that the proposed substring satisfies the DFA. (We make
* the caller do that because in concatenation and iteration nodes, it's
* much faster to check all the substrings against the child DFAs before we
* recurse.) Also, caller must have cleared subexpression match data via
* zaptreesubs (or zapallsubs at the top level).
^ static int cdissect(struct vars *, struct subre *, chr *, chr *);
*/
static int /* regexec return code */
cdissect(
struct vars *v,
struct subre *t,
chr *begin, /* beginning of relevant substring */
chr *end) /* end of same */
{
int er;
assert(t != NULL);
MDEBUG(("cdissect %ld-%ld %c\n", LOFF(begin), LOFF(end), t->op));
switch (t->op) {
case '=': /* terminal node */
assert(t->left == NULL && t->right == NULL);
er = REG_OKAY; /* no action, parent did the work */
break;
case 'b': /* back reference */
assert(t->left == NULL && t->right == NULL);
er = cbrdissect(v, t, begin, end);
break;
case '.': /* concatenation */
assert(t->left != NULL && t->right != NULL);
if (t->left->flags & SHORTER) /* reverse scan */
er = crevcondissect(v, t, begin, end);
else
er = ccondissect(v, t, begin, end);
break;
case '|': /* alternation */
assert(t->left != NULL);
er = caltdissect(v, t, begin, end);
break;
case '*': /* iteration */
assert(t->left != NULL);
if (t->left->flags & SHORTER) /* reverse scan */
er = creviterdissect(v, t, begin, end);
else
er = citerdissect(v, t, begin, end);
break;
case '(': /* capturing */
assert(t->left != NULL && t->right == NULL);
assert(t->subno > 0);
er = cdissect(v, t->left, begin, end);
if (er == REG_OKAY) {
subset(v, t, begin, end);
}
break;
default:
er = REG_ASSERT;
break;
}
/*
* We should never have a match failure unless backrefs lurk below;
* otherwise, either caller failed to check the DFA, or there's some
* inconsistency between the DFA and the node's innards.
*/
assert(er != REG_NOMATCH || (t->flags & BACKR));
return er;
}